Several forms of bed sheet including a pocket or like means for fitting the sheet on a mattress have been described in the prior art. The manner in which the sheets are formed and assembled varies widely. The form and assembly method for a particular sheet may significantly affect its ease of use, for example, in making-up a bed, the neatness and general appearance of the made-up bed, the comfort of a user, and, of course, the cost of manufacture.
McHorter, U.S. Pat. No. 1,865,329, discloses a unitary combination of upper and lower mattress covers, the combination having a relatively deep pocket at the base for receiving a mattress. It appears from the description that such a combined cover would be expensive to produce, difficult to launder, and would require lifting a mattress and holding the mattress in a lifted position in order to fit the pocket over the mattress.
De Voe, U.S. Pat. No. 2,151,357, discloses a single sheet having a much simpler construction than the unitary sheet of McHorter. The sheet of De Voe includes a rectangular main panel having a width greater than the width of a mattress, thus providing overhanging side panels for covering the edges of the mattress. The main panel has a central flap having a width about equal to the mattress. This flap is folded over and stitched to the overhanging side panels for forming a pocket to receive the mattress. The pocket formation scheme appears to have the disadvantage that repeated removal and fitting of the sheet on a mattress could cause the side panel stitching to gradually loosen, thereby degrading the usefulness of the sheet.
Crescenzi, U.S. Pat. No. 2,603,798 discloses a sheet similar in construction to the sheet of De Voe. In particular, the method of stitching a central flap to side panels for forming a pocket is similar, and the sheet appears to exhibit the same potential for loosening the pocket stitches.
A sheet having an apparently stronger pocket is disclosed by Simpson in U.S. Pat. No. 2,679,056. The sheet of Simpson has a very complex, and thus potentially expensive, construction scheme. The construction scheme includes edge beading and corner gussets for strengthening the pocket, and a reserve of folded material to avoid unduly constraining the feet of an occupant of a mattress covered by the sheet.
Large, U.S. Pat. No. 4,245,365, discloses a sheet which includes a shallow pocket having sides formed by diagonal gussets. The sheet includes side panels. The pocket is not secured permanently to the side panels, but may be secured temporarily thereto by a hook and eye arrangement. From the description, it appears necessary to lift the mattress in order to operate the hook and eye arrangement.